Released on June 16, 1978, Grease helped establish John Travolta and Olivia Newton-John as bona fide superstars and went on to become the highest-grossing movie musical of all time (a title the film held until last year, when it was passed by Disney’s live-action Beauty and the Beast). Adapted from the hit Broadway musical of the same name, written by Jim Jacobs and Warren Casey, the Grease we know and love almost didn’t happen in the first place. Once the film rights became available, Hollywood came calling.